The present invention relates to CMOS bandgap voltage reference (BVR) devices and CMOS bandgap current reference (BCR) devices, particularly to provide stable voltage references and current references independent of power supply voltage and temperature.
Stable voltage and current references are essential in many electronic systems. The required performance of voltage and current references can be critical, especially in sensor/transducer systems and data converters. Generally, the ability to integrate an entire data acquisition or sensor/transducer system within a single CMOS VLSI chip is dependent upon being able to realize a CMOS compatible voltage or current reference with very low temperature drift and power supply voltage sensitivity. So far many techniques have been proposed to develop power-supply and temperature independent references.
Among them, the bandgap reference technique has shown the most potential. The principle of bandgap reference was first proposed by Widlar (refer to R. J. Wildar, "New developments in IC voltage regulators", IEEE J. Solid-state Circuits, vol. SC-6, pp. 2-7, Feb. 1979) and has been widely employed to implement stable voltage references in bipolar technology.
In CMOS technology, high-precision bandgap references using parasitic vertical bipolar transistors have recently been proposed (refer to B. S. Song and P. R. Gray, "A precision curvature-compensated CMOS bandgap reference", IEEE J. Solid-State Circuits, vol. SC-18, pp. 634-643, Dec. 1983; J. Michejda and S. K. Kim, "A precision CMOS bandgap reference", IEEE J. Solid-state Circuits,, vol. SC-19, pp. 1014-1021, Dec. 1984; M. G. R. Degrauwe et al. "CMOS voltage references using lateral bipolar transistors", IEEE J. Solid-state Circuits, vol. SC-20, pp. 1151-1157, Dec. 1985; and S. L. Lin and C. A. T. Salama, "A Vbe(T) model with application to bandgap reference design", IEEE J. Solid-state Circuits, vol. SC-20, pp. 1283-1285, Dec. 1985), which demonstrate a temperature drift below 40 ppm/.degree.C.
However, the proposed references either suffer from high offset and drift of CMOS operational amplifiers or have very complex structures. Besides, the power supply voltage sensitivity is not low enough.